Loans and Allowance for Credit Losses - Loans Modified by Modification Type (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2025	Sep. 30, 2024
Financing Receivable, Modified [Line Items]
Modifications	$ 1,244	$ 1,540	$ 3,349	$ 3,661
Percent of Class Total	0.30%	0.40%	0.90%	1.00%
Interest Rate Reduction
Financing Receivable, Modified [Line Items]
Modifications	$ 190	$ 161	$ 436	$ 449
Payment Delay
Financing Receivable, Modified [Line Items]
Modifications	391	414	1,221	1,151
Term Extension
Financing Receivable, Modified [Line Items]
Modifications	482	828	1,197	1,734
Multiple Modifications
Financing Receivable, Modified [Line Items]
Modifications	181	137	495	327
Payment Delay and Term Extension
Financing Receivable, Modified [Line Items]
Modifications	83	85	230	251
Interest Rate Reduction and Term Extension
Financing Receivable, Modified [Line Items]
Modifications	77	44	208	56
Interest Rate Reduction, Payment Delay and Term Extension
Financing Receivable, Modified [Line Items]
Modifications	21	8	57	20
Total loans, excluding loans purchased from GNMA mortgage pools
Financing Receivable, Modified [Line Items]
Modifications	$ 578	$ 952	$ 1,672	$ 2,021
Percent of Class Total	0.20%	0.30%	0.40%	0.50%
Total loans, excluding loans purchased from GNMA mortgage pools | Interest Rate Reduction
Financing Receivable, Modified [Line Items]
Modifications	$ 190	$ 161	$ 436	$ 448
Total loans, excluding loans purchased from GNMA mortgage pools | Payment Delay
Financing Receivable, Modified [Line Items]
Modifications	35	23	306	50
Total loans, excluding loans purchased from GNMA mortgage pools | Term Extension
Financing Receivable, Modified [Line Items]
Modifications	319	732	829	1,477
Total loans, excluding loans purchased from GNMA mortgage pools | Multiple Modifications
Financing Receivable, Modified [Line Items]
Modifications	34	36	101	46
Loans purchased from GNMA mortgage pools
Financing Receivable, Modified [Line Items]
Modifications	$ 666	$ 588	$ 1,677	$ 1,640
Percent of Class Total	0.60%	0.50%	1.50%	1.40%
Loans purchased from GNMA mortgage pools | Interest Rate Reduction
Financing Receivable, Modified [Line Items]
Modifications	$ 0	$ 0	$ 0	$ 1
Loans purchased from GNMA mortgage pools | Payment Delay
Financing Receivable, Modified [Line Items]
Modifications	356	391	915	1,101
Loans purchased from GNMA mortgage pools | Term Extension
Financing Receivable, Modified [Line Items]
Modifications	163	96	368	257
Loans purchased from GNMA mortgage pools | Multiple Modifications
Financing Receivable, Modified [Line Items]
Modifications	147	101	394	281
Commercial | Commercial
Financing Receivable, Modified [Line Items]
Modifications	$ 174	$ 318	$ 455	$ 666
Percent of Class Total	0.10%	0.20%	0.30%	0.50%
Commercial | Commercial | Interest Rate Reduction
Financing Receivable, Modified [Line Items]
Modifications	$ 41	$ 26	$ 79	$ 63
Commercial | Commercial | Payment Delay
Financing Receivable, Modified [Line Items]
Modifications	0	0	1	0
Commercial | Commercial | Term Extension
Financing Receivable, Modified [Line Items]
Modifications	110	292	309	603
Commercial | Commercial | Multiple Modifications
Financing Receivable, Modified [Line Items]
Modifications	23	0	66	0
Commercial | Commercial real estate
Financing Receivable, Modified [Line Items]
Modifications	$ 179	$ 428	$ 444	$ 837
Percent of Class Total	0.40%	0.80%	0.90%	1.70%
Commercial | Commercial real estate | Interest Rate Reduction
Financing Receivable, Modified [Line Items]
Modifications	$ 0	$ 0	$ 0	$ 49
Commercial | Commercial real estate | Payment Delay
Financing Receivable, Modified [Line Items]
Modifications	0	0	0	0
Commercial | Commercial real estate | Term Extension
Financing Receivable, Modified [Line Items]
Modifications	175	401	438	761
Commercial | Commercial real estate | Multiple Modifications
Financing Receivable, Modified [Line Items]
Modifications	4	27	6	27
Consumer | Residential mortgages
Financing Receivable, Modified [Line Items]
Modifications	$ 46	$ 31	$ 330	$ 77
Percent of Class Total	0.00%	0.00%	0.30%	0.10%
Consumer | Residential mortgages | Interest Rate Reduction
Financing Receivable, Modified [Line Items]
Modifications	$ 0	$ 0	$ 0	$ 0
Consumer | Residential mortgages | Payment Delay
Financing Receivable, Modified [Line Items]
Modifications	32	21	295	46
Consumer | Residential mortgages | Term Extension
Financing Receivable, Modified [Line Items]
Modifications	8	3	12	15
Consumer | Residential mortgages | Multiple Modifications
Financing Receivable, Modified [Line Items]
Modifications	6	7	23	16
Consumer | Credit card
Financing Receivable, Modified [Line Items]
Modifications	$ 147	$ 135	$ 355	$ 332
Percent of Class Total	0.50%	0.50%	1.20%	1.10%
Consumer | Credit card | Interest Rate Reduction
Financing Receivable, Modified [Line Items]
Modifications	$ 147	$ 133	$ 352	$ 330
Consumer | Credit card | Payment Delay
Financing Receivable, Modified [Line Items]
Modifications	0	2	3	2
Consumer | Credit card | Term Extension
Financing Receivable, Modified [Line Items]
Modifications	0	0	0	0
Consumer | Credit card | Multiple Modifications
Financing Receivable, Modified [Line Items]
Modifications	0	0	0	0
Consumer | Other retail
Financing Receivable, Modified [Line Items]
Modifications	$ 32	$ 40	$ 88	$ 109
Percent of Class Total	0.10%	0.10%	0.20%	0.30%
Consumer | Other retail | Interest Rate Reduction
Financing Receivable, Modified [Line Items]
Modifications	$ 2	$ 2	$ 5	$ 6
Consumer | Other retail | Payment Delay
Financing Receivable, Modified [Line Items]
Modifications	3	0	7	2
Consumer | Other retail | Term Extension
Financing Receivable, Modified [Line Items]
Modifications	26	36	70	98
Consumer | Other retail | Multiple Modifications
Financing Receivable, Modified [Line Items]
Modifications	$ 1	$ 2	$ 6	$ 3